The objectives of this work are to investigate the separate contributions of the retinal and choroidal circulations to retinal tissue oxygenation and to further develop a new angiographic technique which permits routine evaluation of the choroidal circulation in man. Using micro electrodes, tissue PO2 maps will be made of the various retinal and choroidal layers of the living primate eye. These maps will be made under physiologically normal conditions of ocular circulation, with occluded retinal circulation, occluded choroidal circulation, and with and without hyperbaric oxygenation of arterial blood. A clinical evaluation of the multispectral fundus camera will be made. Following a single intravenous injection of a mixture of sodium fluorescein and indocyanine green dyes, this camera optically separates light reflected from the eye in such a way that the retinal, choroidal arterial and capillary, and choroidal venous circulations are each photographed by a different camera. The three cameras are synchronized so that the filling of these various portions of the ocular circulations can be compared.